. 2023 Jul 21;9:57. doi: 10.1038/s41526-023-00304-0

Table 1.

Safety and scientific hardware requirements.

Safety requirements	Scientific requirements
LOC for cement powder and fresh concrete THL 2: Provide 3 LOC for MCM.	Shape and quality Obtain a homogeneous concrete specimen with a defined geometry and volume: Adjustable axial size of container after mixing to compress fresh concrete and ensure same volume for space and reference ground samples.
Stress resistance Sturdy, pressure and vacuum tight, withstanding stresses resulting from rocket launch, pressure drop during flight and operation on ISS by astronaut.	Exact composition of ingredients Addition of water (and additive, if necessary) at a selected time as centrally as possible to dry and loose stored ingredients to ensure good mixability, no loss of water and exact composition of ingredients.
Chemical stability Alkaline fresh cement: Resistance to basic substances.	Control during operation Transparent container: Control homogenous mixture of components inside container during mixing process.
LOC for additives Additive with THL 1: Provide 2 LOC for syringe.	Mixing mechanics Extraction of mixer with thin and optimal performing mixer blade out of concrete sample after mixing: second chamber to store mixer blade after mixing.
Inspection and control Transparent container: Inspection of built-in parts and connections after assembly.	Exhaustion To ensure mixing quality by astronaut: Design of a mixing tool to facilitate mixing.
Reference tests and batch qualification Batch production of hardware to ensure same quality of all MCMs: tests from a representative number of containers are valid for all.	Quantity Minimum of 3 samples of one mixture and three times the amount for reference ground samples: Affordable batch production of MCMs. Keep upload and download costs as low as possible, requiring a lightweight and small construction.
Mixing tool Design of sturdy mixing tool: No exertion of excessive forces on the hardware.	Extraction Extraction of the specimen without damage: container with smooth surface and light inclination.

Safety requirements

Scientific requirements

LOC for cement powder and fresh concrete

THL 2: Provide 3 LOC for MCM.

Shape and quality

Obtain a homogeneous concrete specimen with a defined geometry and volume: Adjustable axial size of container after mixing to compress fresh concrete and ensure same volume for space and reference ground samples.

Stress resistance

Sturdy, pressure and vacuum tight, withstanding stresses resulting from rocket launch, pressure drop during flight and operation on ISS by astronaut.

Exact composition of ingredients

Addition of water (and additive, if necessary) at a selected time as centrally as possible to dry and loose stored ingredients to ensure good mixability, no loss of water and exact composition of ingredients.

Chemical stability

Alkaline fresh cement: Resistance to basic substances.

Control during operation

Transparent container: Control homogenous mixture of components inside container during mixing process.

LOC for additives

Additive with THL 1: Provide 2 LOC for syringe.

Mixing mechanics

Extraction of mixer with thin and optimal performing mixer blade out of concrete sample after mixing: second chamber to store mixer blade after mixing.

Inspection and control

Transparent container: Inspection of built-in parts and connections after assembly.

Exhaustion

To ensure mixing quality by astronaut: Design of a mixing tool to facilitate mixing.

Reference tests and batch qualification

Batch production of hardware to ensure same quality of all MCMs: tests from a representative number of containers are valid for all.

Quantity

Minimum of 3 samples of one mixture and three times the amount for reference ground samples: Affordable batch production of MCMs.

Keep upload and download costs as low as possible, requiring a lightweight and small construction.

Mixing tool

Design of sturdy mixing tool: No exertion of excessive forces on the hardware.

Extraction

Extraction of the specimen without damage: container with smooth surface and light inclination.